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      SUBROUTINE <a name="CGTRFS.1"></a><a href="cgtrfs.f.html#CGTRFS.1">CGTRFS</a>( TRANS, N, NRHS, DL, D, DU, DLF, DF, DUF, DU2,
     $                   IPIV, B, LDB, X, LDX, FERR, BERR, WORK, RWORK,
     $                   INFO )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  -- LAPACK routine (version 3.1) --
</span><span class="comment">*</span><span class="comment">     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
</span><span class="comment">*</span><span class="comment">     November 2006
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Modified to call <a name="CLACN2.9"></a><a href="clacn2.f.html#CLACN2.1">CLACN2</a> in place of <a name="CLACON.9"></a><a href="clacon.f.html#CLACON.1">CLACON</a>, 10 Feb 03, SJH.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     .. Scalar Arguments ..
</span>      CHARACTER          TRANS
      INTEGER            INFO, LDB, LDX, N, NRHS
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Array Arguments ..
</span>      INTEGER            IPIV( * )
      REAL               BERR( * ), FERR( * ), RWORK( * )
      COMPLEX            B( LDB, * ), D( * ), DF( * ), DL( * ),
     $                   DLF( * ), DU( * ), DU2( * ), DUF( * ),
     $                   WORK( * ), X( LDX, * )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Purpose
</span><span class="comment">*</span><span class="comment">  =======
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  <a name="CGTRFS.26"></a><a href="cgtrfs.f.html#CGTRFS.1">CGTRFS</a> improves the computed solution to a system of linear
</span><span class="comment">*</span><span class="comment">  equations when the coefficient matrix is tridiagonal, and provides
</span><span class="comment">*</span><span class="comment">  error bounds and backward error estimates for the solution.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Arguments
</span><span class="comment">*</span><span class="comment">  =========
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  TRANS   (input) CHARACTER*1
</span><span class="comment">*</span><span class="comment">          Specifies the form of the system of equations:
</span><span class="comment">*</span><span class="comment">          = 'N':  A * X = B     (No transpose)
</span><span class="comment">*</span><span class="comment">          = 'T':  A**T * X = B  (Transpose)
</span><span class="comment">*</span><span class="comment">          = 'C':  A**H * X = B  (Conjugate transpose)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  N       (input) INTEGER
</span><span class="comment">*</span><span class="comment">          The order of the matrix A.  N &gt;= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  NRHS    (input) INTEGER
</span><span class="comment">*</span><span class="comment">          The number of right hand sides, i.e., the number of columns
</span><span class="comment">*</span><span class="comment">          of the matrix B.  NRHS &gt;= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  DL      (input) COMPLEX array, dimension (N-1)
</span><span class="comment">*</span><span class="comment">          The (n-1) subdiagonal elements of A.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  D       (input) COMPLEX array, dimension (N)
</span><span class="comment">*</span><span class="comment">          The diagonal elements of A.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  DU      (input) COMPLEX array, dimension (N-1)
</span><span class="comment">*</span><span class="comment">          The (n-1) superdiagonal elements of A.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  DLF     (input) COMPLEX array, dimension (N-1)
</span><span class="comment">*</span><span class="comment">          The (n-1) multipliers that define the matrix L from the
</span><span class="comment">*</span><span class="comment">          LU factorization of A as computed by <a name="CGTTRF.57"></a><a href="cgttrf.f.html#CGTTRF.1">CGTTRF</a>.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  DF      (input) COMPLEX array, dimension (N)
</span><span class="comment">*</span><span class="comment">          The n diagonal elements of the upper triangular matrix U from
</span><span class="comment">*</span><span class="comment">          the LU factorization of A.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  DUF     (input) COMPLEX array, dimension (N-1)
</span><span class="comment">*</span><span class="comment">          The (n-1) elements of the first superdiagonal of U.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  DU2     (input) COMPLEX array, dimension (N-2)
</span><span class="comment">*</span><span class="comment">          The (n-2) elements of the second superdiagonal of U.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  IPIV    (input) INTEGER array, dimension (N)
</span><span class="comment">*</span><span class="comment">          The pivot indices; for 1 &lt;= i &lt;= n, row i of the matrix was
</span><span class="comment">*</span><span class="comment">          interchanged with row IPIV(i).  IPIV(i) will always be either
</span><span class="comment">*</span><span class="comment">          i or i+1; IPIV(i) = i indicates a row interchange was not
</span><span class="comment">*</span><span class="comment">          required.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  B       (input) COMPLEX array, dimension (LDB,NRHS)
</span><span class="comment">*</span><span class="comment">          The right hand side matrix B.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  LDB     (input) INTEGER
</span><span class="comment">*</span><span class="comment">          The leading dimension of the array B.  LDB &gt;= max(1,N).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  X       (input/output) COMPLEX array, dimension (LDX,NRHS)
</span><span class="comment">*</span><span class="comment">          On entry, the solution matrix X, as computed by <a name="CGTTRS.82"></a><a href="cgttrs.f.html#CGTTRS.1">CGTTRS</a>.
</span><span class="comment">*</span><span class="comment">          On exit, the improved solution matrix X.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  LDX     (input) INTEGER
</span><span class="comment">*</span><span class="comment">          The leading dimension of the array X.  LDX &gt;= max(1,N).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  FERR    (output) REAL array, dimension (NRHS)
</span><span class="comment">*</span><span class="comment">          The estimated forward error bound for each solution vector
</span><span class="comment">*</span><span class="comment">          X(j) (the j-th column of the solution matrix X).
</span><span class="comment">*</span><span class="comment">          If XTRUE is the true solution corresponding to X(j), FERR(j)
</span><span class="comment">*</span><span class="comment">          is an estimated upper bound for the magnitude of the largest
</span><span class="comment">*</span><span class="comment">          element in (X(j) - XTRUE) divided by the magnitude of the
</span><span class="comment">*</span><span class="comment">          largest element in X(j).  The estimate is as reliable as
</span><span class="comment">*</span><span class="comment">          the estimate for RCOND, and is almost always a slight
</span><span class="comment">*</span><span class="comment">          overestimate of the true error.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  BERR    (output) REAL array, dimension (NRHS)
</span><span class="comment">*</span><span class="comment">          The componentwise relative backward error of each solution
</span><span class="comment">*</span><span class="comment">          vector X(j) (i.e., the smallest relative change in
</span><span class="comment">*</span><span class="comment">          any element of A or B that makes X(j) an exact solution).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  WORK    (workspace) COMPLEX array, dimension (2*N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  RWORK   (workspace) REAL array, dimension (N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  INFO    (output) INTEGER
</span><span class="comment">*</span><span class="comment">          = 0:  successful exit
</span><span class="comment">*</span><span class="comment">          &lt; 0:  if INFO = -i, the i-th argument had an illegal value
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Internal Parameters
</span><span class="comment">*</span><span class="comment">  ===================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  ITMAX is the maximum number of steps of iterative refinement.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     .. Parameters ..
</span>      INTEGER            ITMAX
      PARAMETER          ( ITMAX = 5 )
      REAL               ZERO, ONE
      PARAMETER          ( ZERO = 0.0E+0, ONE = 1.0E+0 )
      REAL               TWO
      PARAMETER          ( TWO = 2.0E+0 )
      REAL               THREE
      PARAMETER          ( THREE = 3.0E+0 )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      LOGICAL            NOTRAN
      CHARACTER          TRANSN, TRANST
      INTEGER            COUNT, I, J, KASE, NZ
      REAL               EPS, LSTRES, S, SAFE1, SAFE2, SAFMIN
      COMPLEX            ZDUM
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Arrays ..
</span>      INTEGER            ISAVE( 3 )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           CAXPY, CCOPY, <a name="CGTTRS.139"></a><a href="cgttrs.f.html#CGTTRS.1">CGTTRS</a>, <a name="CLACN2.139"></a><a href="clacn2.f.html#CLACN2.1">CLACN2</a>, <a name="CLAGTM.139"></a><a href="clagtm.f.html#CLAGTM.1">CLAGTM</a>, <a name="XERBLA.139"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC          ABS, AIMAG, CMPLX, MAX, REAL
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Functions ..
</span>      LOGICAL            <a name="LSAME.145"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
      REAL               <a name="SLAMCH.146"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>
      EXTERNAL           <a name="LSAME.147"></a><a href="lsame.f.html#LSAME.1">LSAME</a>, <a name="SLAMCH.147"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Statement Functions ..
</span>      REAL               CABS1
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Statement Function definitions ..
</span>      CABS1( ZDUM ) = ABS( REAL( ZDUM ) ) + ABS( AIMAG( ZDUM ) )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Executable Statements ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Test the input parameters.
</span><span class="comment">*</span><span class="comment">
</span>      INFO = 0
      NOTRAN = <a name="LSAME.160"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( TRANS, <span class="string">'N'</span> )
      IF( .NOT.NOTRAN .AND. .NOT.<a name="LSAME.161"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( TRANS, <span class="string">'T'</span> ) .AND. .NOT.
     $    <a name="LSAME.162"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( TRANS, <span class="string">'C'</span> ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
         INFO = -13
      ELSE IF( LDX.LT.MAX( 1, N ) ) THEN
         INFO = -15
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.174"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="CGTRFS.174"></a><a href="cgtrfs.f.html#CGTRFS.1">CGTRFS</a>'</span>, -INFO )
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Quick return if possible
</span><span class="comment">*</span><span class="comment">
</span>      IF( N.EQ.0 .OR. NRHS.EQ.0 ) THEN
         DO 10 J = 1, NRHS
            FERR( J ) = ZERO
            BERR( J ) = ZERO
   10    CONTINUE
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( NOTRAN ) THEN
         TRANSN = <span class="string">'N'</span>
         TRANST = <span class="string">'C'</span>
      ELSE
         TRANSN = <span class="string">'C'</span>
         TRANST = <span class="string">'N'</span>
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     NZ = maximum number of nonzero elements in each row of A, plus 1
</span><span class="comment">*</span><span class="comment">
</span>      NZ = 4
      EPS = <a name="SLAMCH.199"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>( <span class="string">'Epsilon'</span> )
      SAFMIN = <a name="SLAMCH.200"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>( <span class="string">'Safe minimum'</span> )
      SAFE1 = NZ*SAFMIN
      SAFE2 = SAFE1 / EPS
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Do for each right hand side
</span><span class="comment">*</span><span class="comment">
</span>      DO 110 J = 1, NRHS
<span class="comment">*</span><span class="comment">
</span>         COUNT = 1
         LSTRES = THREE
   20    CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Loop until stopping criterion is satisfied.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Compute residual R = B - op(A) * X,
</span><span class="comment">*</span><span class="comment">        where op(A) = A, A**T, or A**H, depending on TRANS.
</span><span class="comment">*</span><span class="comment">
</span>         CALL CCOPY( N, B( 1, J ), 1, WORK, 1 )
         CALL <a name="CLAGTM.218"></a><a href="clagtm.f.html#CLAGTM.1">CLAGTM</a>( TRANS, N, 1, -ONE, DL, D, DU, X( 1, J ), LDX, ONE,
     $                WORK, N )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Compute abs(op(A))*abs(x) + abs(b) for use in the backward
</span><span class="comment">*</span><span class="comment">        error bound.
</span><span class="comment">*</span><span class="comment">
</span>         IF( NOTRAN ) THEN
            IF( N.EQ.1 ) THEN
               RWORK( 1 ) = CABS1( B( 1, J ) ) +
     $                      CABS1( D( 1 ) )*CABS1( X( 1, J ) )
            ELSE
               RWORK( 1 ) = CABS1( B( 1, J ) ) +
     $                      CABS1( D( 1 ) )*CABS1( X( 1, J ) ) +
     $                      CABS1( DU( 1 ) )*CABS1( X( 2, J ) )
               DO 30 I = 2, N - 1
                  RWORK( I ) = CABS1( B( I, J ) ) +
     $                         CABS1( DL( I-1 ) )*CABS1( X( I-1, J ) ) +
     $                         CABS1( D( I ) )*CABS1( X( I, J ) ) +
     $                         CABS1( DU( I ) )*CABS1( X( I+1, J ) )
   30          CONTINUE
               RWORK( N ) = CABS1( B( N, J ) ) +
     $                      CABS1( DL( N-1 ) )*CABS1( X( N-1, J ) ) +
     $                      CABS1( D( N ) )*CABS1( X( N, J ) )
            END IF
         ELSE
            IF( N.EQ.1 ) THEN
               RWORK( 1 ) = CABS1( B( 1, J ) ) +
     $                      CABS1( D( 1 ) )*CABS1( X( 1, J ) )
            ELSE
               RWORK( 1 ) = CABS1( B( 1, J ) ) +
     $                      CABS1( D( 1 ) )*CABS1( X( 1, J ) ) +
     $                      CABS1( DL( 1 ) )*CABS1( X( 2, J ) )
               DO 40 I = 2, N - 1
                  RWORK( I ) = CABS1( B( I, J ) ) +
     $                         CABS1( DU( I-1 ) )*CABS1( X( I-1, J ) ) +
     $                         CABS1( D( I ) )*CABS1( X( I, J ) ) +
     $                         CABS1( DL( I ) )*CABS1( X( I+1, J ) )
   40          CONTINUE
               RWORK( N ) = CABS1( B( N, J ) ) +
     $                      CABS1( DU( N-1 ) )*CABS1( X( N-1, J ) ) +
     $                      CABS1( D( N ) )*CABS1( X( N, J ) )
            END IF
         END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Compute componentwise relative backward error from formula
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        max(i) ( abs(R(i)) / ( abs(op(A))*abs(X) + abs(B) )(i) )
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        where abs(Z) is the componentwise absolute value of the matrix
</span><span class="comment">*</span><span class="comment">        or vector Z.  If the i-th component of the denominator is less
</span><span class="comment">*</span><span class="comment">        than SAFE2, then SAFE1 is added to the i-th components of the
</span><span class="comment">*</span><span class="comment">        numerator and denominator before dividing.
</span><span class="comment">*</span><span class="comment">
</span>         S = ZERO
         DO 50 I = 1, N
            IF( RWORK( I ).GT.SAFE2 ) THEN
               S = MAX( S, CABS1( WORK( I ) ) / RWORK( I ) )
            ELSE
               S = MAX( S, ( CABS1( WORK( I ) )+SAFE1 ) /
     $             ( RWORK( I )+SAFE1 ) )
            END IF
   50    CONTINUE
         BERR( J ) = S
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Test stopping criterion. Continue iterating if
</span><span class="comment">*</span><span class="comment">           1) The residual BERR(J) is larger than machine epsilon, and
</span><span class="comment">*</span><span class="comment">           2) BERR(J) decreased by at least a factor of 2 during the
</span><span class="comment">*</span><span class="comment">              last iteration, and
</span><span class="comment">*</span><span class="comment">           3) At most ITMAX iterations tried.
</span><span class="comment">*</span><span class="comment">
</span>         IF( BERR( J ).GT.EPS .AND. TWO*BERR( J ).LE.LSTRES .AND.
     $       COUNT.LE.ITMAX ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Update solution and try again.
</span><span class="comment">*</span><span class="comment">
</span>            CALL <a name="CGTTRS.293"></a><a href="cgttrs.f.html#CGTTRS.1">CGTTRS</a>( TRANS, N, 1, DLF, DF, DUF, DU2, IPIV, WORK, N,
     $                   INFO )
            CALL CAXPY( N, CMPLX( ONE ), WORK, 1, X( 1, J ), 1 )
            LSTRES = BERR( J )
            COUNT = COUNT + 1
            GO TO 20
         END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Bound error from formula
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        norm(X - XTRUE) / norm(X) .le. FERR =
</span><span class="comment">*</span><span class="comment">        norm( abs(inv(op(A)))*
</span><span class="comment">*</span><span class="comment">           ( abs(R) + NZ*EPS*( abs(op(A))*abs(X)+abs(B) ))) / norm(X)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        where
</span><span class="comment">*</span><span class="comment">          norm(Z) is the magnitude of the largest component of Z
</span><span class="comment">*</span><span class="comment">          inv(op(A)) is the inverse of op(A)
</span><span class="comment">*</span><span class="comment">          abs(Z) is the componentwise absolute value of the matrix or
</span><span class="comment">*</span><span class="comment">             vector Z
</span><span class="comment">*</span><span class="comment">          NZ is the maximum number of nonzeros in any row of A, plus 1
</span><span class="comment">*</span><span class="comment">          EPS is machine epsilon
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        The i-th component of abs(R)+NZ*EPS*(abs(op(A))*abs(X)+abs(B))
</span><span class="comment">*</span><span class="comment">        is incremented by SAFE1 if the i-th component of
</span><span class="comment">*</span><span class="comment">        abs(op(A))*abs(X) + abs(B) is less than SAFE2.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Use <a name="CLACN2.319"></a><a href="clacn2.f.html#CLACN2.1">CLACN2</a> to estimate the infinity-norm of the matrix
</span><span class="comment">*</span><span class="comment">           inv(op(A)) * diag(W),
</span><span class="comment">*</span><span class="comment">        where W = abs(R) + NZ*EPS*( abs(op(A))*abs(X)+abs(B) )))
</span><span class="comment">*</span><span class="comment">
</span>         DO 60 I = 1, N
            IF( RWORK( I ).GT.SAFE2 ) THEN
               RWORK( I ) = CABS1( WORK( I ) ) + NZ*EPS*RWORK( I )
            ELSE
               RWORK( I ) = CABS1( WORK( I ) ) + NZ*EPS*RWORK( I ) +
     $                      SAFE1
            END IF
   60    CONTINUE
<span class="comment">*</span><span class="comment">
</span>         KASE = 0
   70    CONTINUE
         CALL <a name="CLACN2.334"></a><a href="clacn2.f.html#CLACN2.1">CLACN2</a>( N, WORK( N+1 ), WORK, FERR( J ), KASE, ISAVE )
         IF( KASE.NE.0 ) THEN
            IF( KASE.EQ.1 ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">              Multiply by diag(W)*inv(op(A)**H).
</span><span class="comment">*</span><span class="comment">
</span>               CALL <a name="CGTTRS.340"></a><a href="cgttrs.f.html#CGTTRS.1">CGTTRS</a>( TRANST, N, 1, DLF, DF, DUF, DU2, IPIV, WORK,
     $                      N, INFO )
               DO 80 I = 1, N
                  WORK( I ) = RWORK( I )*WORK( I )
   80          CONTINUE
            ELSE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">              Multiply by inv(op(A))*diag(W).
</span><span class="comment">*</span><span class="comment">
</span>               DO 90 I = 1, N
                  WORK( I ) = RWORK( I )*WORK( I )
   90          CONTINUE
               CALL <a name="CGTTRS.352"></a><a href="cgttrs.f.html#CGTTRS.1">CGTTRS</a>( TRANSN, N, 1, DLF, DF, DUF, DU2, IPIV, WORK,
     $                      N, INFO )
            END IF
            GO TO 70
         END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Normalize error.
</span><span class="comment">*</span><span class="comment">
</span>         LSTRES = ZERO
         DO 100 I = 1, N
            LSTRES = MAX( LSTRES, CABS1( X( I, J ) ) )
  100    CONTINUE
         IF( LSTRES.NE.ZERO )
     $      FERR( J ) = FERR( J ) / LSTRES
<span class="comment">*</span><span class="comment">
</span>  110 CONTINUE
<span class="comment">*</span><span class="comment">
</span>      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="CGTRFS.371"></a><a href="cgtrfs.f.html#CGTRFS.1">CGTRFS</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

</pre>

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